Integration of Cu-Based MOF with COOH-Functionalized MWCNTs to Enhance the Electrochemical Performance of Modified Screen-Printed Carbon Electrode for Folic Acid Determination

In the present work, we have prepared a simple, convenient, and sensitive voltammetric method for the determination of folic acid, based on its enhanced electrochemical oxidation at the surface of a modified screen-printed carbon electrode (SPCE). Cu-based metal-organic framework integrated with COOH-functionalized multi-walled carbon nanotubes (Cu-MOF/COOH-f-MWCNTs) was synthesized by the solvothermal method and used for the modification of SPCE. The integration of Cu-MOF with COOH-f-MWCNTs demonstrated good analytical performance in the voltammetric determination of folic acid, which can be confirmed by the enhanced oxidation peak current and the decreased oxidation peak potential of folic acid at the surface of Cu-MOF/COOH-f-MWCNTs/SPCE in comparison to other electrodes. From the quantitative measurements using differential pulse voltammetry, the oxidation peak currents of folic acid were found to be proportional to its concentration in the range of 0.01 to 400.0 μM, and the limit of detection of 0.003 μM is achieved. Finally, the applicability of the developed sensing platform for folic acid determination was confirmed by analyzing orange juice and tablet samples with recoveries from 97.8% to 103.9% and the relative standard deviations were ≤3.6%.